Japanese Laid-Open Patent Publication No. 2012-144061 discloses a motor assist bicycle that drives a motor to assist driving of a wheel when pushing and walking the bicycle in addition to when riding the bicycle. The motor assist bicycle includes a walk switch. When the walk switch is pushed, a control device of the motor assist bicycle determines whether or not the rider is walking the bicycle from the depression force applied to the pedals and the rotation speed of the crankshaft. When the control device determines that the rider is walking the bicycle, the control device drives the motor in a predetermined drive mode, namely, a walk mode. The walk switch is also used as a switch that adjusts assist drive force during normal riding.
When the rider operates the switch during normal riding to adjust the auxiliary drive force, the motor may be driven in the walk mode even though the rider does not intend to do so.